서로 다른 고정층을 가진 스핀 토크 나노 발진기에서 자성 방울 생성 조건 비교

정선재,Johan Åkerman 한국물리학회 2023 새물리 Vol.73 No.1

We compared magnetic droplet nucleation boundaries in different spin–torque nano-oscillators with fixed layers of Co and [Co/Pd] multilayers. The nucleation conditions for magnetic droplets were determined as a functions of magnetic field and current and from the onset of a low-frequency noise. The spin–torque nano-oscillator with Co fixed layer showed an inverse proportional relation between magnetic fields and currents in a low magnetic field and a linear proportional relation in a high magnetic field. In the device constituting the Co/Pd multi-layer as a fixed layer, a linear proportional relation was observed in a whole range of magnetic field. Further details will be discussed in this study.

USN 기반 개인 안전벨트 모니터링 시스템의 구현

정선재,임재홍,Jeong, Seon-Jae,Yim, Jae-Hong 한국정보통신학회 2015 한국정보통신학회논문지 Vol.19 No.3

The safety-related accident in which the field operators of all sorts of industrial sites don't fasten the seat belt properly and which it generates is the tendency that it increases constantly every year. By sounding the announcement sound in case the operator did not fasten the seat belt and the person seat belt monitoring system proposed in this paper progressed the work the operator fastened the seat belt properly. In addition, at the same time with that, since the administrator monitored the seat belt wearing or no of the operators on a real time basis the safety-related accident which did not wear the safety equipment properly and which it generates was prevented. 각종 산업현장의 현장 작업자들이 안전 벨트를 제대로 착용하지 않아서 발생하는 안전사고는 매년 꾸준히 증가하고 있는 추세이다. 본 논문에서 제안하는 개인 안전벨트 모니터링 시스템은 작업자가 안전벨트를 착용하지 않고 작업을 진행할 경우 알림음을 울림으로써 작업자가 안전벨트를 제대로 착용하도록 하였다. 또한 그와 동시에 관리자가 실시간으로 작업자들의 안전 벨트 착용 여부를 모니터링함으로써 안전장비를 제대로 착용하지 않아서 발생하는 안전사고를 예방할 수 있도록 하였다.

17GHz 대역의 저출력 Electronic Scanner 개발

정선재,전성호,이영섭,이광근,임재홍,Jeong, Seon-Jae,Jeon, Sung-Ho,Lee, Young-Sub,Lee, Kwang-Keun,Yim, Jae-Hong 한국정보통신학회 2019 한국정보통신학회논문지 Vol.23 No.4

오늘날 해양 업계에서 활용되는 대부분의 탐지 시스템은 고출력의 X-Band 대역을 활용한 장비들이 대다수이다. 이러한 X-Band 대역의 주파수를 활용하는 대부분의 탐지 시스템들은 광범위한 탐지 성능 이득을 기대할 수 있지만, 장비의 특성상 크고 무거우며 정밀한 탐지를 요하는 분야에서는 적합하지 않다는 한계점을 지닌다. 본 논문에서는 Ku-Band 대역 중 17GHz 주파수 대역에서 2W 미만의 저출력으로 주변의 물표뿐만 아니라 바다의 파랑까지 탐지가 가능한 Electronic Scanner를 설계 및 제작하고, 시험을 진행하였다. 저전력에서도 충분한 탐지성능을 확보하기 위하여 고성능의 패치 어레이 안테나 및 도플러 효과를 활용하여 충분한 탐지 성능을 확보하였으며, 이에 대한 시험 결과 충분한 가능성을 확인할 수 있었다. Today, most detection systems used in the marine industry are the majority of devices operating in the high-power X-band bands. While most detection systems using these frequencies in the X-Band band can expect a wide range of detection performance, they are not suitable for precision detection and have the limitation that they are large and heavy. In this paper, we designed, fabricated and tested an electronic scanner capable of detecting not only the surrounding objects but also the ocean waves at a low power of less than 2W in the 17GHz frequency band of the Ku-Band. A high-performance patch array antenna and Doppler effect were utilized to obtain sufficient detection performance even at low power. As a result of the test, it was confirmed that the performance was sufficiently valuable.

Beacon을 활용한 선박 탑승자 위치확인 시스템의 구현

정선재,임재홍,Jeong, Seon-Jae,Yim, Jae-Hong 한국정보통신학회 2016 한국정보통신학회논문지 Vol.20 No.1

In this paper, we propose a system that tracks the position of the passengers and sailors using a Bluetooth-based Beacon in the ship. The position of the tracking passengers, sometimes fatal emergencies of the rescue team, such as the sinking of the ship is utilized in order to efficiently and quickly rescue the passengers, and the collected data can be utilized additionally by grasping the flow of human traffic patterns. The system proposed in this paper, install MAC data acquisition called AP (Access Point) for each cabin, and in the installed AP retrieves Tag of the information provided to the passenger and collected. A Tag has only its own MAC Address to the privacy, no user information is not collected. All data communication by sending and receiving MAC Address was only to ensure anonymity. 본 논문에서는 선박 내에서 Bluetooth 기반의 Beacon을 활용하여 탑승객 및 선원들의 위치를 추적하는 시스템에 대하여 제안하였다. 추적된 탑승객들의 위치는 선박 침몰과 같은 치명적인 위급상황 발생시 구조대가 효율적으로 신속하게 승객들을 구조하는 데 활용될 수 있으며, 수집된 데이터들은 사용자들의 동선 패턴을 파악하여 부가적으로 활용될 수 있다. 이 논문에서 제안된 시스템은, 선실마다 AP(Access Point)라고 불리는 MAC 데이터 수집 장치를 설치하고, 설치된 AP에서는 탑승자들에게 제공된 Tag의 정보를 검색하고 수집한다. Tag는 개인 정보 보호를 위하여 고유의 MAC Address만을 가지며, 별도의 사용자 정보는 수집하지 않는다. 모든 데이터 통신은 MAC Address만을 송 수신하도록 하여 익명성을 보장하였다.

[Co/Ni]-NiFe 교환스프링 자석의 자성 특성에 관한 연구

정선재,Johan Åkerman 한국자기학회 2021 韓國磁氣學會誌 Vol.31 No.1

We investigate the magnetic proprieties of [Co/Ni]-NiFe exchange spring magnets having 1) different thick NiFe layers, 2) two different stack sequences, and 3) different thick Cu spacer between [Co/Ni] multilayers and NiFe layer. We show that the magnetization tilt angle can be tuned from out-of-plane (OOP) to in-plane (IP) by varying the NiFe thickness (tNiFe) larger than tNiFe = 1.5 nm, while similar transition occurs from thinner tNiFe when NiFe layer was deposited earlier than [Co/Ni] multilayers. Finally, we insert Cu spacer between [Co/Ni] multilayers and NiFe layer to figure out how strongly these are coupled. We find the rapid decoupling behavior as a increase of Cu spacer thickness (tCu) between 0.5 and 1.3 nm.

Mental Health and Psychological Intervention Amid COVID-19 Outbreak: Perspectives from South Korea

정선재,전진용 연세대학교의과대학 2020 Yonsei medical journal Vol.61 No.4

Not applicable

제한된 공간내 분무의 유동특성 실험

정선재,이상용 대한기계학회 1992 대한기계학회논문집 Vol.16 No.5

A series of experiment has been performed on the spray characteristics in a cylindrical confined space with the injection pressure taken as a parameter. By using a single-hole patternator and the Malvern particle sizer, the spray mass flux, drop size and volume concentration distributions along the radial and axial directions were obtained ; the line-of- sight data by Malvern particle sizer have been converted to the ring-of-sight data by using the tomographical transformation techniqe. The experimental results show that, due to the restriction on the ambient gas entrainment by the wall boundary, the effective spray angle is increasing. The spray drops were measured to be smaller in the confined space because of a large number of floating small drops by recirculation of the gas phase and the breakup of large drops by the wall collision. Also the details on the flow behavior of the confined spray are discussed.

Association of Selected Medical Conditions With Breast Cancer Risk in Korea

정선재,송민교,최지엽,송난,박수경,유근영,강대희 대한예방의학회 2013 Journal of Preventive Medicine and Public Health Vol.46 No.6

Objectives: To estimate the effect of medical conditions in the population of Korea on breast cancer risk in a case-control study. Methods: The cases were 3242 women with incident, histologically confirmed breast cancer in two major hospitals interviewed between 2001 and 2007. The controls were 1818 women each admitted to either of those two hospitals for a variety of non-neoplastic conditions. Information on each disease was obtained from a standardized questionnaire by trained personnel. Odds ratios (ORs) for each disease were derived from multiple logistic regression adjusted for age, age of menarche, pregnancy, age of first pregnancy, and family history of breast cancer. Results: Among all of the incident breast cancer patients, pre-existing diabetes (OR, 1.33; 95% confidence interval [CI], 0.99 to 1.78), hypertension (OR, 1.46; 95% CI, 1.18 to 1.83), thyroid diseases (OR, 1.26; 95% CI, 1.00 to 1.58), and ovarian diseases (OR, 1.70; 95% CI, 1.23 to 2.35) were associated with an increased risk of breast cancer when other factors were adjusted for. In a stratified analysis by menopausal status, pre-existing hypertension (pre-menopause OR, 0.80; 95% CI, 0.48 to 1.34 vs. post-menopause OR, 1.87; 95% CI, 1.44 to 2.43; p-heterogeneity <0.01) and ovarian disease (pre-menopause OR, 4.20; 95% CI, 1.91 to 9.24 vs. post-menopause OR, 1.39; 95% CI, 1.02 to 1.91; p-heterogeneity 0.01) showed significantly different risks of breast cancer. Conclusions: Our results suggest the possibility that medical conditions such as hypertension affect breast cancer development, and that this can differ by menopausal status. Our study also indicates a possible correlation between ovarian diseases and breast cancer risk.

17㎓ 대역의 저출력 Electronic Scanner 개발

정선재(Seon-Jae Jeong),전성호(Sung-Ho Jeon),이영섭(Young-Sub Lee),이광근(Kwang-Keun Lee),임재홍(Jae-Hong Yim) 한국정보통신학회 2019 한국정보통신학회논문지 Vol.23 No.4

적외선 카메라를 통한 순찰 인공지능 드론 알고리즘 개발

정선재(SunJae Jeong),신송희(SongHee Shin),박지수(JiSu Park),이두한(DooHan Lee),한승희(SeungHee Han) 한국콘텐츠학회 2022 한국콘텐츠학회 종합학술대회 논문집 Vol.2022 No.7